Radiator size is fine. People buy parts and dont kknow how to get the best out of each part which is the problem these days.

The issue with the halfsize is that you have a big gap next to the radiator and what happens when your driving along is that the air is bypassing the radiator and going through that big gap next to it. Think about it. Block that big gap next to the radiator and the air has no where to go but through the radiator. But then what can happen now is that the air will go over the top of the radiator. So thats where diversion plates come into the picture. Air is pushed back down and through the radiator. You are now using your radiator to its optimum potential.

Hope that helps.